Circuit breaker with improved reset means



Oct. 15, 1963 F. B. DESIO ETAL 0 CIRCUIT BREAKER WITH IMPROVED RESET MEANS Filed Feb. 6, 1961 Y 61 1 Wilt J3 United States Patent 3,167,232 CIRCUIT BREAKER WITH h' /iPRGVED RESET MEANS Frank 3. Basis, Meiro'se Paris, and John F. Mart nis, St. Charles, ill, assignors ta Litteliuse, Incorporated,

Des Plaines, 111., a corporation of illinois Fiied Feb. 6, 1951, er. No. 824% 6 Claims. (Ql. 2tltl-ll3) This invention relates to circuit breakers of the thermostatic type having a trip free manud reset feature and, which also may serve as an on and off manual switch. More specifically it has reference to a circuit breaker of the type aforesaid which is fool-proof against deliberate manual closure of the circuit during overload of a value causing automatic opening, but which allows reset upon subsidence of the overload current to a safe or continuous rating value.

The principal object of the invention is to provide a device adapted to carry a normal or so-called continuous rating current but which will open automatically upon passage of current of a value in excess of normal and which will remain in open condition until manually reset, i.e. reclosed, the reset means being so arranged that the device cannot be manually held in the closed position if the overload condition persists but will continue to remain open. However upon cessation of overload the switch may be manually reset.

Another object resides in a resetting actuator or button for the purpose aforesaid which may also be employed to open the circuit manually and to maintain the same open until shifted to on, whereupon the automatic functioning of the device as a circuit breaker is resumed.

Other objects and advantages will become apparent from the ensuing description which, taken with the accompanying drawing, discloses a preferred mode of carrying the invention into practice.

In this drawing:

FIG. 1 is a perspective view of a device embodying the invention, as assembled for use;

FIG. 2 is a cross section, somewhat enlarged, taken on the line 2-2 of FIG. 1;

FIG. 3 is a cross section taken on the line 3-4: of FIG. 2;

FIG. 4 is a cross section taken on the line 4--4 of FIG. 2;

FIG. 5 is a detail in perspective of the spring associated with the reset button to bias the same normally to 01 condition of the switch;

FIG. 6 is a detail in perspective of the reset button minus the spring of FIG. 5; and

FIG. 7 is a detail in perspective of the base of the device and its thereto secured movable switch member and associated fixed contact.

Broadly regarded, the invention circuit breaker comprises a base mounting a pair of terminals to connect the device in the circuit. To one terminal is secured a temperature-controlled switch element, e.g. of the bimetallic type, responsive to the value of the current through the switch whereby normal value thereof permits the element to maintain a normal position engaging a fixed contact but which, when subjected to a temperature corresponding to some value of current beyond the rated maximum, will disengage the fixed contact and open the circuit, and which, upon reduction in current, i.e. temperature, will reengage the fixed contact and reclose the circuit automatically. If, upon reclosure, the overload condition has been alleviated the contacts will remain closed whereas, if such is not the case, the switch element will re-open the same, and such re-cycling will continue until the overload condition is relieved or the switch is manually re-opened by actuation of the reset atsazsz Patented Get. 15, lfi3 actuator to off. The switch element is made suiiiciently wider than the contact button carried thereby for cooperation with shoulders on the reset actuator or may be provided with lateral projections for the same purpose.

The reset actuator is rendered shiftable in suitable guides whereby the shoulders aforesaid may, alternatively, take up a first position precluding deliberate reclosing of the contacts which have been opened in response to an overload until the overload has been relieved, or a second position in which the switch is placed in off condition. Such shoulders are each provided with a ramp which, when the switch blade is heated by overload and opens, enter under the blade thereby preventing recyoling of the element and reclosing of the contacts. If, during overload, the reset actuator is manually shifted to on, i.e. reset position, the switch blade will continue to recycle. A spring associated with the reset actuator constantly urges the same toward the position at which the shoulders will underlie the switch blade so that, if the reset actuator, once moved to on, is released during the overload, the switch blade is prevented from closing the contacts. Upon cessation of overload the switch may be reset by shifting the reset actuator to on. If the switch is to be opened manually irrespective of an overload condition, the reset actuator is shifted to off, whereat the shoulders enter under the laterally-projecting sides of the switch blade to withhold the same positively from closing pending subsequent manual restoration of the actuator to on.

Adverting now to the drawing, we have shown, by way of example, a combined automatic circuit breaker and manual switch embodying the principles of the invention. There is shown a base 10 of electrically insulating material having an essentially flat top surface 11 for a purpose to appear, and a peripheral recess 12 to frictionally receive a box-like cover 13, which fit may be implemented by any well-known means, e.g. a detent arrangement.

Carried in the base '19, as by integrally molding the same therein, are terminal posts 15 and 16 extending below the base in threaded ends for attachment of any suitable form of electrical terminals whereby the device may be connected in the circuit to be protected or interrupted. Desirably, the posts 15 and 16 are knurled at 19 and 2t) and suitably shouldered as shown to insure permanence, as is well known. At its inner end the post 15 has a switch blade or element 22 secured thereto as by providing a hole in the blade fitted over a reduced portion of the post and over which latter a washer 23 is placed, the end of the post being upset. If desired, said reduced end may be in the nature of a spline receiving a complementary hole in the switch blade for more reliable lateral positioning thereof.

The switch blade 22 is shown as of substantially fiatsided, oval contour and is associated with or incorporates means which will cause the blade to flex about its fixed end in response to the rise in temperature concomitant upon increase in current. One desirable form thereof is a bimetal slightly dished over its extent in order to obtain snap action when the contacts are opened, sometimes termed oil-can action by analogy to the function of the base of a conventional squirt type of oil can. The normal bias to which the switch blade is subjected is in a direction maintaining the device closed. The desired heating effect results when the contacts are closed and overload current flows through the blade. The desired snap action may be improved by providing a hole 25 in the center. Other forms of switch blade may be availed of provided that laterally extending portions are presented for coaction with the shoulder portions or cams of the reset actuator shortly to be detailed. For example the switch blade may be a generally elongated member provided adjacent its distal'end with a pair of laterally extending wings for such coaction.

- The free end of the blade 22 is provided with a conventional contact button 31. Such contact is adapted for circuit closing and opening action with respect to a similar fixed contact button 32 borne on the upper end of the terminal post 316. In the example, the geometry of the assembly is such that a cavity 33 is formed in the base 10 providing clearance. for the contacts 31 and 32. From the foregoing it will have become apparent that, during flow of rated current the contacts will remain closed by virtue of the bias applied to the blade 22 and that, upon passage of overload current, the blade will flex or be deflected to open the contacts whereupon the temperature responsive means cools and attempts to reestablish the circuit. The arrangement whereby the movable contact is prevented from actually touching the fixed contact pending manual reset will be described hereinafter. If, at the time reset is attempted, the overload has not been relieved the switch will repeat such abortive opening and closing action until the reset actuator is moved to OFF position, as will appear.

The reset and off actuator 40 is best illustrated inv FIG. 6 and it comprises a member of electrically insulating material guided for longitudinal shifting movement with respectto the base Ml, i.e. from right to left and vice versa as seen in FIG. 2. The actuator comprises a top wall 41 with depending side walls 4242 slidable on.

{the flat top surface 11 of the base 10 receiving, between them, the blade 22 and being guided by the interior of the side walls of the cover 13 (FIG. 3). Sliding, vertical fit with respect to the fiat top 11 of the base and the interior of the top wall of the cover 13 is obtained by suitable choice of the height of the actuator, e.g. the distance between a pad 46 thereon and the bottom edge of the walls 42-42 (FIG. 2).

The pad 46 bears the indicia ON and OFF arranged to be exposed alternatively in a window 51 in the top of the cover 13 through which an operating finger 52 protrudes for access.

The actuator 40 is constantly subject to leftward bias (ofi position) under the urging of a spring member 61 (FIG. of somewhat box-like form having a top wall 62 apertured at 63 to fit snugly over the pad 46, a notch 64 to define a bridge 65 underlying an extended part 66 of the pad 46 and a partial right wall 67 abutting the righthand face of the actuator whereby the spring member is lodged in operative relation with the actuator. The height of the pad 46 is only slightly greater than the thickness of the spring member and the pad has minimum clearance with the cover 13. Thus, the latter aflords further retention. It will be noted that the several clearances are exaggerated in FIGS. 2 and 3 for clarity of comprehension. The partial end wall 67 continues as a cantilevered leaf spring 71 bearing against the adjacent end wall of the cover 13.

The lateral walls 4242 of the actuator are each provided with a projection or shoulder 73 having a substantiallyhorizontal face 73a and an inclined face 73b adapted to enter beneath the switch blade 22.

The operation will now be described. Assuming the switch is in its on position, the actuator 40 being to the right (full lines in FIG. 2), the surfaces 73a and 73b are engaged by the edge of the distal end of the switch blade 22. Parenthetically it is to be noted that, while the full line showing of FIG. 2' might indicate interference there is actually none by reason of the quadrantal corners of the distal end of the blade 22. In this position of the actuator the resiliency of the blade closes the contacts and the circuit is completed and also holds the actuator in the on position. Upon occurrence of overload, the blade opens thecircuit and will undertake to recycle the opening and closing operations. However, upon opening action, the leaf spring 71 urges the actuator as to the left to 4 project the surfaces 73:: under the blade 22 (broken lines A in FIG. 2). Thus, the blade will be held open until the switch is manually reset by operation of the actuator to the right, withdrawing the surfaces 7.3a and freeing the blade 22.

If the overload is persistent and the operator attempts to restore the circuit by deliberately holding the actuator on, the blade Z-Zwill simply continue to recycle until the current has been reducedto the rated value, whereafter the function is as described above.

To turn the switch off, the actuator 40 is manually pushed to the left or off position, forcing the surfaces 73a under the blade 22. Entry of the surfaces 73a beneath the blade is facilitated by the leading, inclined surfaces 7311. 1

From the foregoing it will have become clear that the invention comprehends a circuit-interrupting device which will protect againstsome predetermined maximum value of current and which will remain in the open condition until manually reclosed following decline of overload current to a safe value. Otherwise expressed, during recycling action in the presence of overload current, the device cannot be deliberately held closed. Also, manual opening of the switch is also provided.

While we have shown a particular embodiment of our invention, it will be understood, of course, that we do not wish to be limited thereto since many modifications may be made and we, therefore, contemplate by the appended claims to cover any such modification as falls disengage the fixed contact, means connecting said fixed contact and blade in the circuit for controlling the current flow therethrough, said blade normally resiliently engaging the fixed contact to close the circuit but being movable upon excess current flow in the circuit to disengage the fixed contact to openthe'circuit, an actuator guided for shifting movement on said base and shiftable between on and off positions, a projection on the actuator having a first surface for engaging and maintaining the blade out of engagement with the fixed contact when the actuator is in its off position, spring means for biasing the actuator to its oii position, a handle on the actuator for shifting the actuator to its on position against the action of the spring means to allow the blade to engage V the fixed contact, said projection on theactuator having an inclined second surface merging with the first surface and engaging the blade when the blade is engaging the fixed contact for maintaining the actuator in its on position against the action of the spring means, said inclined second surface on said projection engaging the blade and said spring means biasing the actuator to its off position operating to aid in disengaging the blade from the fixed contact upon excess current flow in the circuit,.and said inclined second surface on said projection engaging the blade and said actuator when manually moved by said handle to its off position operating manually to disengage the blade from the fixed contact regardless of the current flow in the circuit.

2. A circuit breaker adapted to interrupt an electrical circuit upon an excess current flow therein comprising, an

electrical insulating base, a fixed contact mounted on said base, a resilient bimetallic switch blade mounted on said base and adapted to engage and disengage the fixed conclose the circuit but being movable upon excess current flow in the circuit to disengage the fixed contact to open the circuit, an actuator guided for shifting movement on said base and shiftable between on and off positions, said shiftable actuator including end walls and a face therebetween and a pad protruding from the face, a metallic member having a fiat part overlying the face of the actuator with the aperture closely fitting said pad and a part engaging at least one end wall of the actuator to locate said member relative to the shiftable actuator, a portion of said metallic member being struck out therefrom to constitute a cantilever leaf spring meacs for engaging a fixed part associated with the base for biasing the actuator to its off position, a projection on the actuator having a first surface for engaging and maintaining the blade out of engagement with the fixed contact when the actuator is in its off position, a handle extending from the pad on the actuator for shifting the actuator to its on position against the action of the spring means to allow the free end of the {blade to engage the fixed contact, said projection on the actuator having a second surface merging with the first surface and engaging the blade when the blade is engaging the fixed contact for maintaining the actuator in its on position against the action of the spring means.

3. A combination switch and circuit breaker adapted to interrupt an electrical circuit upon manual manipulation or upon an excess current fiow in the electrical circuit comprising, an electrical insulating base, a fixed contact mounted on said base, a resilient bimetallic switch blade mounted on said base and adapted to engage and disengage the fixed contact, means connecting said fixed contact and blade in the circuit for controlling the current flow therethrough, said blade normally resiliently engaging the fixed contact to close the circuit but being movable upon excess current flow in the circuit to disengage the fixed contact to open the circuit, an actuator guided for shifting movement on said base and shiftable between on and oft positions, said shiftable actuator including end walls and a face therebetween and a pad protruding from the face, a metallic member having a flat part overlying the face of the actuator with the aperture closely fitting said pad and a part engaging at least one end wall of the actuator to locate said member relative to the shiftable actuator, a portion of said metallic member being struck out therefrom to constitute a cantilever leaf spring means for engaging a fixed part associated with the base for biasing the actuator to its 01f position, a projection on the actuator having a first surface for engaging and maintaining the blade out of engagement with the fixed contact when the actuator is in its off position, a handle on the actuator for shifting the actuator to its on position against the action of the spring means to allow the blade to engage the fixed contact, said projection on the actuator having an inclined second surface merging with the first surface and engaging the blade when the blade is engaging the fixed contact for maintaining the actuator in its on position against the action of the spring means, said inclined second surface on said projection engaging the blade and said spring means biasing the actuator to its off position operating to aid in disengaging the blade from the fixed contact upon excess current flow in the circuit, and said inclined second surface on said projection engaging the blade and said actuator when manually moved by said handle to its off position operating manually to disengage the blade from the fixed contact regardless of the current fiow in the circuit.

4. A combination switch and circuit breaker adapted to interrupt an electrical circuit upon manual manipulation or upon an excess current flow in the electrical circuit comprising, an electrical insulating base, a fixed con tact mounted on said base, a resilient bimetallic switch blade mounted at one end on said base and having its free end engaging and disengaging the fixed contact, means connecting said fixed contact and blade in the circuit for controlling the current flow therethrough, said blade normally resiliently engaging the fixed contact to close the circuit but being movable upon excess current flow in the circuit to disengage the fixed contact to open the circuit, an actuator guided for shifting movement on said base and shiftable between on" and off positions, a projection on the actuator having a first surface for engaging and maintaining the free end of the blade out of engagement with the fixed contact when the actuator is in its off position, spring means for biasing the actuator to its off position, a handle on the actuator for shifting the actuator to its on position against the action of the spring means to allow the free end of the blade to engage the fixed contact, said projection on the actuator having an inclined second surface merging with the first surface and engaging the free end of the blade when the blade is engaging the fixed contact for maintaining the actuator in its on position against the action of the spring means, said inclined second surface on said projection engaging the free end of the blade and said spring means biasing the actuator to its off position operating to aid in disengaging the blade from the fixed contact upon excess current flow in the circuit, and said inclined surface on said projection engaging the free end of the blade and said actuator when manually moved by said handle to its oif position operating manually to disengage the blade from the fixed contact regardless of the current flow in the circuit.

5. A circuit breaker adapted to interrupt an electrical circuit upon an excess current fiow therein comprising, an electrical insulating base, a fixed contact mounted on said base, a resilient bimetallic switch blade mounted at one end on said base and having its free end engaging and disengaging the fixed contact, means connecting said fixed contact and blade in the circuit for controlling the current fiow therethrough, said blade normally resiliently engaging the fixed contact to close the circuit but being movable upon excess current fiow in the circuit to disengage the fined contact to open the circuit, an actuator guided for shifting movement on said base and shiftable between on and off positions, said shiftable actuator including end walls and a face therebetween and a pad protruding from the face, a metallic member having a fiat part overlying the face of the actuator with the aperture closely fitting said pad and a part engaging at least one end Wall of the actuator to locate said member relative to the shift-able actuator, a portion of said metallic member being struck out therefrom to constitute a cantilever leaf spring means for engaging a fixed part associated with the base for biasing the actuator to its ofi position, a projection on the actuator having a first surface for engaging and maintaining the free end of the blade out of engagement with the fixed contact when the actuator is in its off position, a handle extending from the pad on the actuator for shifting the actuator to its on position against the action of the spring means to allow the free end of the blade to engage the fixed contact, said projection on the actuator having a second surface merging with the first surface and engaging the free end of the blade when the blade is engaging the fixed contact for maintaining the actuator in its on position against the action of the spring means.

6. A combination switch and circuit breaker adapted to interrupt an electrical circuit upon manual manipulation or upon an excess current flow in the electrical circuit comprising, an electrical insulating base, -a fixed contact mounted on said base, a resilient bimetallic switch blade mounted at one end on said base and having its free end engaging and disengaging the fixed contact, means connecting said fixed contact and blade in the circuit for controlling the current flow therethrough, said blade normally resiliently engaging the fixed contact to close the circuit but being movable upon excess current flow in the circuit to disengage the fixed contact to open the circuit, an actuator guided for shifting movement on said base and shiftable between on and off positions,

said shiftable actuator including end Walls and a face therebetween and a pad protruding from the face, a,

ing the free end of the blade out of engagement with the.

fixed contact when the actuator is in its off position, a handle extending from the pad on the actuator for shitting the actuator to its on position against the action of the spring'means to allow the free end of the blade to engage the fixed contact, said projection on the actuator having an inclined second surrface merging with the first surface and engaging the free end of the blade when the blade is engaging the fixed contact for maintaining the actuator in its on position against the action of the spring means, said inclined second surface on said projection engaging the free end of the blade and said spring means biasing the actuator to its off position operating to aid in disengaging the blade from the fixed contact upon excess current flow in the circuit, and said inclined second surface on said projection engaging the free end of the blade and said actuator when manually moved by said handle to its off position operating manually to H disengage the blade from the (fixed contact regardless of the current flow in the circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,575,469 7 Waterbury Mar. 2, 1926 2,487,422 Carle Nov. 8, 1949 2,488,818 Kitman Nov. 22, 1949 2,520,873 Bean Aug. 29, 1950 2,743,333 Epstein Apr. 24, 1956 2,993,968 'Ellithorpe July 25, 1961 Jan-J- 

2. A CIRCUIT BRAKER ADAPTED TO INTERRUPT AN ELECTRICAL CIRCUIT UPON AN EXCESS CURRENT FLOW THEREIN COMPRISING, AN ELECTRICAL INSULATING BASE, A FIXED CONTACT MOUNTED ON SAID BASE, A RESILIENT BIMETALLIC SWITCH BLADE MOUNTED ON SAID BASE AND ADAPTEED TO ENGAGE AND DISENGAGE THE FIXED CONTACT, MEANS CONNECTING THE CURRENT FLOW THERETHROUGH, SAID CIRCUIT FOR CONTROLLING THE CURRENT FLOW THERETHROUGH, SAID BLADE NORMALLY RESILIENTLY ENGAGING THE FIXED CONTACT TO CLOSE THE CIRCUIT BUT BEING MOVABLE UPON EXCESS CURRENT FLOW IN THE CIRCUIT TO DISENGAGE THE FIXED CONTACT TO OPEN THE CIRCUIT, AN ACTUATOR GUIDED FOR SHIFTING MOVEMENT ON SAID BASE AND SHIFTABLE BETWEEN "ON" AND "OFF" POSITIONS, SAID SHIFTABLE ACTUATOR INCLUDING END WALLS AND A FACE THEREBETWEEN AND A PAD PORTRUDING FROM THE FACE, A METALLICE MEMBER HAVING A FLAT PART OVERLYING THE FACE OF THE ACTUATOR WITH THE APERTURE CLOSELY FITTING SAID PAD AND A PART ENGAGING AT LEAST ONE END WALL OF THE ACTUATOR TO LOCATE SAID MEMBER RELATIVE TO THE SHIFTABLE ACTUATOR TO PORTION OF SAID METALLIC MEMBER BEING STRUCK OUT THEREFROM TO CONSTITUTE A CANTILEVER LEAF SPRING MEANS FOR ENGAGING A FIXED PART ASSOCIATED WITH THE BASE FOR BIASING THE ACTUATOR TO ITS "OFF" POSITION, A PROJECTION ON THE ACTUACTOR HAVING A FIRST SURFACE FOR ENGAGING AND MAINTAINING THE BLADE OUT OF ENGAGEMENT WITH THE FIXED CONTACT WHEN THE ACTUATOR IS IN ITS "OFF" POSITION, A HANDLE EXTENDING FROM THE PAD ON THE ACTUATOR FOR SHIFTING THE ACTUATOR TO ITS "ON" POSITION AGAINST THE ACTION OF THE SPRING MEANS TO ALLOW THE FREE END OF THE BLADE TO ENGAGE THE FIXED CONTACT, SAID PROJECTION ON THE ACTUATOR HAVING A SECOND SURFACE MERGING WITH THE FIRST SURFACE AND ENGAGING THE BLADE WHEN THE BLADE IS ENGAGING THE FIXED CONTACT FOR MAINTAINING THE ACTUATOR IN ITS "ON" POSITION AGAINST THE ACTION OF THE SPRING MEANS. 